Knucklehead, Shovelhead, and Panhead bring fond memories to many fans of the Harley Davidson motorcycle. These were the nicknames given to the overhead-valve engines that powered the 61EL Harley Davidson motorcycle from 1936 to 1984. Another famous name in the history of Harley Davidson motorcycle is the Electric Glide. This is the type of Harley engine that powered the Harley Davidson motorcycle Peter Fonda rode in the movie "Easy Rider." Many Harley riders consider the 1936 61EL Knucklehead to be the bike that put Indian Motorcycle company out of business while others claim it was the bike that saved Harley Davidson from bankruptcy. Who can say but both agree this was Harley's first proper production overhead-valve twin and, introduced in 1936, this Harley Davidson motorcycle was a ground breaking machine.

The primary new feature on the bike was its all-new overhead valve Knucklehead engine which, for the first time on a Harley Davidson motorcycle, also had a reticulating lubrication system. But the 61EL wasn't just about improved technology -- it was also one of the best looking bikes that Harley ever built, and elements of its design can be seen in the Harley Davison cruisers of today.